Gemini 3.5 Flash vs GPT-5.6 Terra — Side-by-side pricing
Side-by-side API pricing and tokenizer details for Gemini 3.5 Flash (Google) and GPT-5.6 Terra (OpenAI).
Side-by-side pricing
| Feature | Gemini 3.5 Flash | GPT-5.6 Terra |
|---|---|---|
| Provider | OpenAI | |
| Input (per 1M tokens) | $1.50 | $2.50 |
| Output (per 1M tokens) | $9.00 | $15.00 |
| Long-context pricing | Flat rate at any prompt size | Over 272K tokens: $5.00 in / $22.50 out |
| Context caching | Yes — 90% off cached tokens | Yes — 90% off cached tokens |
| Batch API discount | 50% off | 50% off |
| Context window | 1M tokens | 1.1M tokens |
| Tokenizer | Gemini tokenizer | o200k_base (tiktoken) |
Real-world cost example
1,000 API requests per month, each with 500 input tokens and 200 output tokens (500K input + 200K output total).
Gemini 3.5 Flash
$2.5500
Input: $0.7500 +Output: $1.8000
GPT-5.6 Terra
$4.2500
Input: $1.2500 +Output: $3.0000
Gemini 3.5 Flash is 40% cheaper for this workload — saving $1.7000 per month at this volume.
Frequently asked questions
Yes, Gemini 3.5 Flash is cheaper for the typical workload above. At $1.50/1M input and $9.00/1M output tokens, it costs $2.5500 versus $4.2500 for GPT-5.6 Terra — a 40% difference. Note that GPT-5.6 Terra switches to long-context pricing above 272K prompt tokens, so for very long prompts this gap does not scale linearly.
Gemini 3.5 Flash supports a 1M token context window. GPT-5.6 Terra supports a 1.1M token context window. A larger context window lets you include more text — documents, conversation history, or code — in a single API call.
Gemini 3.5 Flash supports context caching (90% off repeated tokens). It offers a 50% Batch API discount. GPT-5.6 Terra supports context caching (90% off repeated tokens). It offers a 50% Batch API discount.
No, they use different tokenizers. Gemini 3.5 Flash uses the Gemini tokenizer, while GPT-5.6 Terra uses o200k_base (tiktoken). Different tokenizers split text differently, so the same prompt will produce different token counts on each model — the effective cost difference may be larger or smaller than the per-token price difference alone suggests.
Gemini 3.5 Flash (Google): $1.5 input / $9 output per 1M tokens. GPT-5.6 Terra (OpenAI): $2.5 input / $15 output per 1M tokens. Rates shown before caching or batch discounts.
For an 80% output / 20% input workload — typical for code generation or long-form writing — Gemini 3.5 Flash costs $7.5000 per 1M total tokens and GPT-5.6 Terra costs $12.5000. Gemini 3.5 Flash is 40% cheaper for this pattern. For your exact ratio, paste a real prompt into the calculator above.
Gemini 3.5 Flash has a 1M-token context window — approximately 750K words or ~3K pages of standard text. GPT-5.6 Terra has a 1.1M-token context window — approximately 788K words or ~3K pages. (Estimates assume ~0.75 words per token.)
Calculate costs for your actual prompt
Paste your prompt into the calculator and get exact token counts using each model's real tokenizer — all in your browser.
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